So, I've recently gotten back into this, and tried to get better at playing it. The problem is, I think my controller might suck for it. I have a Logitech Precision, and it doesn't seem good at a "rotation" attacks (that is; ones with commands like "down, down right, right"). This might be because its D-pad isn't a straight "plus" shape, but rather, is embedded in a SEGA Genesis-style circle that probably has four additional buttons under there for diagonal movement; pressing these on accident might screw things up.

Now, some people might wonder if it's actually me that sucks at MUGEN. I'm surprisingly open to that humble possibility, but the problem with that theory is that I've tried to play it with my keyboard, and done better. For all I know, most people do that, but I rather doubt it, as the keyboard still isn't great for it.

So can anyone here who's got a lot of experience explain what all this is about? Does my controller suck, does keyboard suck, and what's the best way to play MUGEN?

Its the natural Mugen Delay, if you want to play acurrate try joy to key(or even try to use a ps2 clone joystick adapted to a arcade stick on it lol), xpadder give too much lag as the natural Mugen controller detection.

well, on my experience, I cannot decently play mugen or any other fighting game with a controller.I play really well with the keyboard, and I have the advantage over controller that OP mentions of not being able to pull off some commands with the cross padand I have an arcade controller that I bought specifically for playing fighting games but I ended using for all my games, since I grew in the arcades golden age and I got accustomed to that control format.